Abstract

The work embodied in this dissertation is mainly concerned with the isolation and characterization of chemical constituents from two terrestrial medicinal plants and their possible biological activities. The isolated compounds whether new or have been previously reported in the literature, were characterized by using various sophisticated spectroscopic techniques available at this institution. This dissertation is split in two parts, A and B.
Part A BIOACTIVE CHEMICAL CONSTITUENTS OF SYMPLOCOS RACEMOSA
The phytochemical investigation of Symplocos racemosa Roxb. resulted in the isolation of eight new chemical constituents, out of these, five are phenolic glycosides of salirepin series, two are C-glycosides while one is a naturally ethyl substituted glycoside. The new compounds include benzoylsalireposide (49), symploracemoside (50), symplomoside (51), I-O-ethyl brachiose-3'-acetate (52), symploveroside (53), symplososide (54), symonoside (55) and symplocomoside (56). Except compound 52, all these chemical constituents displayed inhibitory potential against snake venom phosphodiesterase I. In addition to this enzyme, 49, 54, 55, and 56 also possessed inhibitory activity against thymidine phosphorylase. Against lipoxygenase 49, 52, and 56 showed inhibition but other constituents could not be screened due to insufficient quantities, while compound 56 was also found to be a urease inhibitor. The structures of new chemical constituents are shown below:
Part B BIOACTIVE CHEMICAL CONSTITUENTS OF COMMIPHORA MUKUL
The phytochemical studies on the Commiphora mukul Engl. led to the isolation of two lignans, epiexcelsin (21) and 5'-demetaoxyepiexcelsin (22), which belong to the fused bistetrahydrofuran series and are reported for the first time from this species. These lignans displayed inhibitory potential against a-glucosidase and chymotrypsin enzymes